Using a cold chisel

A cold chisel is a piece of equipment designed to cut through metal sheet whilst working at room temperature.  The chisel is made from a section of hexagonal bar which has been suitably hardened and then tempered at the cutting tip to give the material the required properties to withstand the force exerted upon it during its use. The process usually relies on application of force usually using a ball-pein hammer to cut through the desired section of metal.

To assist in the cutting of the material it is essential to perform preparatory stages to make sure that the accuracy of the removal of the material is appropriate.

The images and text below demonstrate the stages that lead up to and through the process of removing a square section from the centre of a metal plate.

Check the drawing to make sure that you are going to mark out the correct size.  Also check that the material is the correct outside sizes, if it isn’t then you will need to bring it to size through marking out and then removal of excess material. 

Use a set of odd leg calipers to mark the line the correct distance in from the edges of the metal plate.

This is the finished size of the opening that needs to be created.  So a smaller offset square is created 5mm further in from the first square.

This smaller square is the one that will be  ‘chain drilled’ and so a number of centre punch marks are set out along the smaller square.

In this instance an 8mm drill will be used for the chain drilling.  This should result in the final set of holes being close to the desired outside line and leave 2mm of material between each of the spaces to be cut through with the cold chisel.

After chain drilling this is the result.

Because the material is to large to support in a school workshop engineers vice the material is G Clamped to the side of the anvil.  This will help prevent the material deforming as it is cold chiselled.

This is how it looks after 3 sides have been cut with the cold chisel.  After each side is cut the material is rotated so that you are always working along the edge of the anvil.

After the material has been cut away from the centre of the material it requires careful filing using a coarse file, then a second cut file to bring it down to the required size and finish.